Transgenic expression in tobacco of a poly-proctolin construct leading to production of the bioactive peptide

Short peptides can be expressed in plants using synthetic genes encoding multiple copies of the peptide spaced by dibasic endoproteolytic cleavage sites. A synthetic gene encoding an array of repeated copies of proctolin, a very well characterized insect myotropic peptide, spaced by Arg residues, was synthesized and expressed in tobacco plants. The successful production of bioactive proctolin from the precursor in transgenic plants was demonstrated by immunoblot, HPLC, mass spectrometry and a bioassay based on the contraction of isolated cockroach hindgut. These results suggest that in planta, as in animals and yeasts, endopeptidases of the serine proteases family may be involved in precursor processing.